Method and apparatus for making a compartmentalized tire sealant strip

ABSTRACT

A method for making a compartmentalized sealant strip and barrier assembly  10  has the steps of co-extruding a barrier strip  9  of non-sealant elastomeric material with a plurality of projecting linear extending walls  9   c  and a sealant strip  11  wherein the sealant strip  11  is formed on one side of the barrier strip  9  filling the space between the plurality of projecting walls  9   c  to form a plurality of linearly extending rows of sealant  11  across the transverse width of the co-extrusion to form the compartmentalized sealant strip and barrier assembly  10.

TECHNICAL FIELD

This invention relates to a method and apparatus for making a puncturesealant strip assembly for use in a tire. More particularly acompartmentalized sealant strip assembly formed as an extruded strip.

BACKGROUND OF THE INVENTION

It is known in the prior art to apply puncture sealants made of puncturesealing rubber or plastic material on the crown portion of the tire sothat when a sharp object such as a nail pierces the tire, the tiresealant forms a seal around the puncture. Tire sealants of this naturetend to flow or be soft resulting in a tendency to migrate towards thecenter portion of the tire due to centrifugal force as the tire isrotated at high speeds. Thus the outer portions of the crown havereduced sealant volume due to migration of the sealant towards thecenter. It is known in the prior art to compartmentalize a sealant intomultiple cells such as shown in U.S. Pat. No. 2,877,819 or U.S. Pat. No.4,388,261. One disadvantage to compartmentalizing the sealant intomultiple cells is that the manufacturing process is costly. Further,having too many compartments may impede the effective flow of thesealant needed to seal a puncture. Further, it was conventional wisdomthat using an extruder to manufacture the sealant into compartments iscostly and requires additional manufacturing steps.

In US patent publication 2009/0159182 A1 published Jun. 25, 2009 RobertLammlein Jr. proposed an apparatus employing conveyor and strip applyingdevices to assemble three or more sealant strips in an assembly havingsealant material in strips with non-sealant dividers separating thestrip of sealant. This publication, “Method and Apparatus For Building APuncture Sealant Preassembled Component” was believed to be a simple wayto assemble the sealant into a partitioned strip of sealant as apreassembled component. Once built, the assembly could be delivered to atire building machine to be used in the manufacture of a self-sealingtire. Mr. Lammlein's invention achieved a partitioned sealant layer bythe use of an apparatus employing conveyors and strip appliers to attachdivider strips between adjacent sealant strips.

Similarly in JP 2006-14925, slits were cut into a sealant strip andnon-sealant rubber dividers were placed in the slits to achieve asimilar result.

In JP 2003-334868 an upper or lower non-sealant layer with a pluralityof projecting walls was used to form partitions as circumferential ribsto divide the sealant into hoop like annular rings about the tire oralternatively will transverse and circumferential partition walls toform numerous cells of sealant material. A rather large and not easilyovercome difficulty in this sealant strip assembly was removal ofentrapped air. As every tire builder can easily appreciate havingpockets of air in an uncured green tire can cause large problems duringhigh temperature curing. Great care is taken to avoid entrapped air andtherefore most tire builders would want to avoid any assembly thatpromotes the occurrence of entrapped air.

In all the prior art attempts to use sealants in tires it has been agoal to minimize the amount of sealant material used to keep tire weightincreases to a minimum. This is important as the added weight tend toincrease tire heat build-up during driving and tends to increase thevehicle's fuel consumption. Accordingly, engineers have been workinghard to provide a self-sealing tire resistant to punctures, but withoutdecreasing the tire uniformity or performance.

A second objective is to provide this self-sealing feature at a very lowadditional cost. For the most part of a tire's useful life, flats arenot that common an occurrence, but when they occur, it is almost alwaysat a most inconvenient time for the driver. Many vehicles have airpressure sensors mounted in the wheels to alert the driver to seekassistance and repair. Some vehicles are equipped with self-supportingrunflat tires with reinforced sidewalls, but these are rather costly.The sealant tire is a good reliable lower cost solution that won'tsustain tire pressure on large openings, but will certainly keep a tirefrom losing air pressure from a nail or screw puncture. These puncturesare generally the most common cause of flat tires and for the typicalvehicle a sealant or self-sealing tire is the best insurance againsttire punctures because it is believed the most affordable solution.

The present invention as described as follows provides what is believedto be a most cost efficient approach to manufacturing acompartmentalized sealant strip assembly.

SUMMARY OF THE INVENTION

A method for making a compartmentalized sealant strip and barrierassembly has the steps of co-extruding a barrier strip of non-sealantelastomeric material with a plurality of projecting linear extendingwalls and a sealant strip wherein the sealant strip is formed on oneside of the barrier strip filling the space between the plurality ofprojecting walls to form a plurality of linearly extending rows ofsealant across the transverse width of the co-extrusion to form thecompartmentalized sealant strip and barrier assembly. The step ofco-extruding may further include the step of: forming the projectingwalls on an inclined angle relative to a plane perpendicular to thewidth of the strip. In a preferred method for making a compartmentalizedsealant strip and barrier assembly, the co-extruded sealant strip andbarrier assembly has a center plane perpendicular to the width of thestrip and the projecting walls are inclined from the barrier stripextending laterally outwardly away from the center plane to form asealant barrier wall to prevent sealant migration toward the centerplane of the sealant strip and barrier assembly. The step ofco-extruding further has the step of: forming the barrier strip withlateral edges that extend beyond the lateral outermost sealant strips oneach side of the assembly, the lateral edges being bonding surfaces toseal the sealant strip and barrier assembly into an uncured rubber layerwhen assembled into an unvulcanized tire. The barrier strip of theassembly is formed as a co-extrusion to be a top layer overlaying thecompartmentalized sealant strips when the assembly is built into a tire.The inclined barrier walls are co-extruded extending a depth between 50to 100 percent of the thickness of the sealant strips, preferably theinclined walls extend to a depth equal to the thickness of the sealantstrips.

The invention includes an intermediate article of manufacture formed asa preassembly of a co-extruded compartmentalized sealant strip andbarrier strip assembly which has a co-extrusion of a barrier layer orstrip of non-sealant elastomeric material having a plurality ofprojecting linearly extending barrier walls formed on one side of thebarrier strip; and a co-extrusion of a plurality of linearly extendingrows of sealant of a thickness at least filling spaces between thebarrier walls of the barrier strip, the combination forming thecompartmentalized sealant strip and barrier assembly. The projectingbarrier walls extend from the one side of the barrier strip to a depthbetween 50 to 100 percent of the thickness of the sealant strips. Thethickness of the sealant strips is between 0.5 to 2 cm. The projectingbarrier walls are inclined relative to a plane perpendicular to a widthof the strip and barrier assembly. The co-extruded assembly has a centerplane perpendicular to the width of the assembly and the projectingwalls are inclined from the barrier strip extending laterally outwardlyaway relative to the center plane to form a sealant barrier to preventsealant migration toward the center plane of the assembly. The barrierstrip has a pair of lateral edges, each lateral edge extends laterallybeyond the lateral outermost sealant strip on each side of the assembly,the lateral edges having a width which provides a bonding surface toseal the sealant and barrier assembly to an uncured rubber layer whenassembled into an unvulcanized tire. The barrier strip of the assemblyis a top or a radially outer layer or a radially outer layer of thecompartmentalized sealant strip and barrier assembly when built into atire. The barrier strip has a layer thickness of 1 mm to 4 mm and theprojecting barrier walls have a thickness equal to or less than thethickness of the layer thickness. The barrier walls preferably extend tothe full thickness of the sealant strips and have exposed ends.

The sealant is preferably comprised of, based upon parts by weight per100 parts by weight of said partially depolymerized butyl rubberexclusive of carbon black: (A) a partially organoperoxide-depolymerizedbutyl rubber as a copolymer of isobutylene and isoprene, wherein saidbutyl rubber, prior to such depolymerization, is comprised of about 0.5to about 5 percent units derived from isoprene, and correspondingly fromabout 95 to about 99.5 weight percent units derived from isobutylene;(B) particulate reinforcing filler comprised of: (1) about 20 to about50 phr of synthetic amorphous silica, or (2) about 15 to about 30 phrsynthetic amorphous silica, preferably precipitated silica, and about 5to about 20 phr of clay, or (3) about 15 to about 30 phr syntheticamorphous silica and about 5 to about 20 phr of calcium carbonate, or(4) about 15 to about 30 phr synthetic amorphous silica, about 5 toabout 15 phr of clay and about 5 to about 15 phr of calcium carbonate;(C) from zero to 6 phr of short organic fibers; (D) a colorant of otherthan a black color wherein said colorant is selected from at least oneof organic pigments, inorganic pigments and dyes; and (F) from zero toabout 20 phr of rubber processing oil.

This preassembly allows an inventive tire to be assembled. This sealanttire has a pair of annular beads; a pair of elastomeric apexes, one apexabove each bead; at least one carcass ply extending between and wrappedabout each bead; a belt reinforcing structure overlaying the carcass; atread overlaying the belt reinforcing structure; an air impervious innerliner extending between the beads underlying the carcass for forming anair chamber; and a compartmentalized sealant strip and barrier assemblypositioned between the carcass and inner liner under the beltreinforcing structure. The compartmentalized sealant strip and barrierassembly is a co-extrusion of a co-extrusion of barrier strips ofnon-sealant elastomeric material having a plurality of projectinglinearly extending barrier walls formed on one side of the barrierstrip. A co-extrusion of a plurality of linearly extending rows ofsealant to a thickness at least fills spaces between the barrier wallsof the barrier strip. The combination forms the compartmentalizedsealant strip and barrier assembly. The preassembly of the strip isachieved by a unique die for forming the barrier and sealant assembly.

DEFINITIONS

As used herein and in the claims,

“Aspect Ratio” means the ratio of a tire's section height to its sectionwidth.

“Axial” and “axially” mean the lines or directions that are parallel tothe axis of rotation of the tire.

“Carcass” means a laminate of tire ply material and other tirecomponents cut to length suitable for splicing, or already spliced, intoa cylindrical or toroidal shape. Additional components may be added tothe carcass prior to its being vulcanized to create the molded tire.

“Circumferential” means lines or directions extending along theperimeter of the surface of the annular tread perpendicular to the axialdirection; it can also refer to the direction of the sets of adjacentcircular curves whose radii define the axial curvature of the tread asviewed in cross section.

“Cord” means one of the reinforcement strands, including fibers, whichare used to reinforce the plies.

“Inner Liner” means the layer or layers of elastomer or other materialthat form the inside surface of a tubeless tire and that contain theinflating fluid within the tire.

“Laminate structure” means an unvulcanized structure made of one or morelayers of tire or elastomer components such as the inner liner,sidewalls, and optional ply layer.

“Ply” means a cord-reinforced layer of elastomer-coated, radiallydeployed or otherwise parallel cords.

“Radial” and “radially” mean directions radially toward or away from theaxis of rotation of the tire.

“Radial Ply Structure” means the one or more carcass plies or which atleast one ply has reinforcing cords oriented at an angle of between 65degrees and 90 degrees with respect to the equatorial plane of the tire.

“Radial Ply Tire” means a belted or circumferentially-restrictedpneumatic tire in which the ply cords which extend from bead to bead arelaid at cord angles between 65 degrees and 90 degrees with respect tothe equatorial plane of the tire.

“Sidewall” means a portion of a tire between the tread and the bead.

“Skive” or “skive angle” refers to the cutting angle of a knife withrespect to the material being cut; the skive angle is measured withrespect to the plane of the flat material being cut.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure, operation, and advantage of the invention will becomefurther apparent upon consideration of the following description takenin conjunction with the accompanying drawings wherein:

FIG. 1 is a schematic view of a cross section of tire with a sealantcompartmentalized strip made in accordance with the present invention;

FIG. 2 is a cross sectional view of a prior art sealant;

FIG. 3 a is a cross sectional view of a first embodiment of thecompartmentalized sealant strip and barrier assembly;

FIG. 3 b is a cross sectional view of a second embodiment of the sealantand barrier assembly;

FIGS. 4-7 are various views of an extruder die for forming the presentinvention sealant strip and barrier assembly

FIG. 8 is a perspective view of the extruder die in a die head or holdershowing the forming of the compartmentalized sealant strip and barrierassembly.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, there is illustrated a cross-sectional view ofa self-sealing pneumatic tire constructed in accordance with theinvention. The tire may be any type of tire. For example, a truck tire,a light truck tire or a passenger tire. The tire 2 includes sidewalls 3,a supporting tire carcass 4, a pair of beads 5, an inner liner 6, alayer of the compartmentalized sealant strip and barrier assembly 10 ofthe present invention, and an outer circumferential tread 8. Thesidewalls 3 extend radially inward from the axial outer edges of thetread portion 8 to join the respective beads. The carcass 4 acts as asupport structure for the tread and sidewalls, and is comprised of oneor more layers of cord reinforced ply 7. The compartmentalized sealantstrip and barrier assembly 10 is shown disposed between the inner liner6 and an elastomeric cover layer such as for example, a rubber layer,the ply layer 7 or an optional additional barrier layer. The barrierlayer or strip 9 of the assembly 10 has a width sized to cover thesealant strip layers 11 such as from shoulder to shoulder, or mayfurther extend down into the bead area between the ply and inner liner.The sealant assembly may also be disposed at different locations such asthe sidewall region. The tread region 8 forms a crown region of thecarcass. In the interior region of the tread, there is generally foundone or more belts 18. The surface region of the tread forms a treadpattern.

The sealant strips 11 may be made from any suitable sealant compositionknown to those skilled in the art, such as rubber or elastomercompositions and plastic compositions. One suitable polymer compositionsuitable for use is described in U.S. Pat. No. 4,895,610, the entiretyof which is incorporated by reference. The polymer compositionsdescribed therein include the following composition by weight: 100 partsof a butyl rubber copolymer, about 10 to about 40 parts of carbon black,about 5 to about 35 parts of an oil extender, and from about 1 to 8parts of a peroxide vulcanizing agent. A second polymer compositionincludes the following composition by weight: 100 parts of a butylrubber copolymer, about 20 to about 30 parts of carbon black, about 8 toabout 12 parts of an oil extender, and from about 2 to 4 parts of aperoxide vulcanizing agent.

The sealant strips 11 may also comprise a colored polymer composition asdescribed in U.S. Pat. No. 7,073,550, the entirety of which isincorporated herein by reference. The colored polymer composition iscomprised of, based upon parts by weight per 100 parts by weight of saidpartially depolymerized butyl rubber exclusive of carbon black: (A) apartially organoperoxide-depolymerized butyl rubber as a copolymer ofisobutylene and isoprene, wherein said butyl rubber, prior to suchdepolymerization, is comprised of about 0.5 to about 5, preferablywithin a range of from 0.5 to one, percent units derived from isoprene,and correspondingly from about 95 to about 99.5, preferably within arange of from 99 to 99.5, weight percent units derived from isobutylene;(B) particulate reinforcing filler comprised of: (1) about 20 to about50 phr of synthetic amorphous silica, preferably precipitated silica, or(2) about 15 to about 30 phr synthetic amorphous silica, preferablyprecipitated silica, and about 5 to about 20 phr of clay, preferablykaolin clay, or (3) about 15 to about 30 phr synthetic amorphous silica,preferably precipitated silica, and about 5 to about 20 phr of calciumcarbonate, (4) about 15 to about 30 phr synthetic amorphous silica,preferably precipitated silica, about 5 to about 15 phr of clay,preferably kaolin clay, and about 5 to about 15 phr of calciumcarbonate; (C) from zero to 6, alternately about 0.5 to about 5, phr ofshort organic fibers (D) a colorant of other than a black color whereinsaid colorant is selected from at least one of organic pigments,inorganic pigments and dyes, preferably from organic pigments andinorganic pigments; (E) from zero to about 20, alternately about 2 toabout 15, phr of rubber processing oil, preferably a rubber processingoil having a maximum aromatic content of about 15 weight percent, andpreferably a naphthenic content in a range of from about 35 to about 45weight percent and preferably a paraffinic content in a range of about45 to about 55 weight percent.

Another sealant polymer composition which may be utilized by theinvention is described in U.S. Pat. No. 6,837,287, the entirety of whichis hereby incorporated by reference.

Further, any sealant polymer composition may also be used with theinvention that has a polymer composition of butyl rubber and anorganoperoxide vulcanizing agent which becomes activated at hightemperatures above 100 degrees C.

FIG. 1 illustrates one example of a sealant configuration for a tire.The sealant strips 11 are comprised of two or more zones, preferably twoor more axially outer zones 20, 22 located between the shoulder portionand the center portion of the tire and one or more axially inner zones21 located in the center portion of the tire 2.

The thickness of the sealant in each of the zones 20, 21 and 22 can varygreatly in an unvulcanized puncture sealant-containing tire. Generally,the thickness of the sealant composition layer may range from about 0.13cm (0.05 inches) to about 1.9 cm (0.75 inches). In passenger and trucktires it is normally desired for the sealant composition layer to have athickness of about 0.32 cm (0.125 inches). The sealant width may varydepending upon the tire size, but may typically be in the range of 1 to6 inches (2.5 cm to 15 cm).

After the unvulcanized pneumatic rubber tires of this invention areassembled they are vulcanized using a normal tire cure cycle. The tiresof this invention can be cured over a wide temperature range dependingsomewhat upon the size of the tire and the degree of desireddepolymerization of the butyl rubber as well as the thickness of thesealant layer itself) and sufficient to at least partially depolymerizesaid sealant precursor layer to the aforesaid storage modulus (G′)physical property.

With reference to FIG. 2, a prior art sealant is illustrated as a strip100 which has been extruded having a width and a thickness sufficient toprovide a puncture sealing layer in a tire to prevent air loss fromnails or screws. As shown this prior art extrusion of the strip 100would be formed as a single layer extrusion and then additional layersof material would be used to encapsulate it during the tire buildingprocess.

With reference to FIG. 3 a, the compartmentalized tire sealant strip andbarrier assembly 10 is illustrated. The sealant strip and barrierassembly 10 is shown with a nail 1 puncturing the sealant strip 11. Asshown, there is a barrier layer 9 extending from lateral edges 9 a, 9 band above the sealant strips 20, 21, 22. This barrier layer or strip 9has a plurality of barrier walls 9 c shown extending from the barrierstrip through and dividing various strips of sealant material. As shown,the axially outer sealant strips 20 and 22 are shown as well as theintermediate sealant strips 21. As illustrated, the barrier walls 9 care inclined relative to a center plane (cp) of the co-extrusionassembly 10. In such a way that the barrier walls 9 c extend outwardlyfrom the barrier layer 9 through the sealant strips 11 to an end 9 d. Asshown, the barrier walls 9 c can be inclined extending the full depth ofthe sealant strip 11. Alternatively, it is sufficient if the barrierwalls 9 c only extend 50 to 100 percent of the thickness of the sealantmaterial. This is true because during circumferential spinning androtation of the tire sealant strips 11 become the semi-liquid orgelatinous sealant material after vulcanization, and when it is spun ittends to want to flow radially outwardly, as such shorter inclinedbarrier walls 9 c are sufficient to entrap the sealant 11 in itslocation sufficiently to keep the sealant material in its propercompartmental strip zone 20, 21, 22. This is extremely important in thatif the sealant is free to move as in the prior art of FIG. 2, all of thesealant during driving conditions would tend to rotate to the center ofthe tire as it revolves. This would result in a very minimal amount ofsealant material being left in the shoulder regions of the tire. Inorder to prevent this, the inclined barrier walls 9 c are formed as apart of co-extrusion of the barrier layer 9 and these barrier walls 9 ckeep each of the spaces sufficiently filled with sealant material thatshould a nail puncture the tire there will be sufficient sealantmaterial to prevent air seepage from the tire. A careful review of thebarrier strip 9 shows that by having the barrier walls 9 c inclined asillustrated a nail 1 puncturing the sealant 11 would be able to receivesealant from two zones due to the inclination of the barrier walls 9 c.This ability to receive a flow sealant as shown ensures that the tire 2will be adequately sealed should a puncture occur that strikes near oradjacent the barrier walls 9 c. If the barrier walls 9 c were notinclined as shown, it would be possible for a nail to penetrate slidingagainst a barrier wall in such a fashion that the barrier wall wouldprovide an open passage for air to escape from the tire 2 as the sealant11 would be unable to get past the wall to completely surround the nailbecause the nail is rubbing against the barrier wall. By being inclinedas illustrated it is impossible for the nail 1 not to be completelysurrounded by sealant material should it puncture into the area of theinclined wall 9 c. Alternatively, should the nail 1 puncture in themiddle of the zone 21, the sealant strip 11 will perform more thanadequately as it is directly in the path of the sealant materialunobstructed by any walls or other surfaces. As shown, these zones 20,21, 22 of sealant material formed as strips when wrapped around the tirecreate annular rings or hoops of sealant material. The compartmentalizedbarrier walls 9 c enable the sealant strips 11 to stay in their properposition throughout the life of the tire. This means that the sealantmaterial can have a thickness preferably between 0.5 cm and 4 cm orless. The less amount of sealant material used in the assembly 10 meansthat the tire 2 will provide sufficient nail puncture resistance whileminimizing the amount of additional weight added to the tire 2. Thisenables the compartmentalized sealant strip barrier assembly 10 to bemanufactured in a cost efficient manner in regards to its overallmaterial usage.

With reference to FIG. 3 b, a second embodiment of the tire is shownwhere additional sealant strips 11 are employed. In this embodiment, theaxially outer sealant strip zones 20 and 22 are illustrated with sevenintermediate strip zones 21 provided. While this number can vary foreach tire 2, it is sufficient to note that all of these can be assembledin a simple one step co-extrusion process that is described hereafter.

The illustrated compartmentalized sealant strip and barrier assembly 10is best manufactured by a dual co-extrusion process. This co-extrusionprocess requires a unique die 30 to be provided. This die 30 is bestillustrated in FIGS. 4-7. With reference to FIG. 4 a perspective view ofthe die 30 is shown. A pair of lateral die ends 31, 32 are shown. Inbetween the die ends 31, 32 is an upper surface 33, this upper surface33 forms the barrier layer 9 profile as shown. This barrier layerprofile also forms the pair of lateral edges 9 a and 9 b which areformed in depressions 34, 35 in the die. These depressions 34, 35 canstep up to the flat surface 33 extending between the lateral depressions34, 35 these features combined form the profile for overall barrierlayer 9 in the die 30. At an outlet portion of the die 30 downstream thebarrier material will pass over a plurality of openings or holes 40.These holes 40 project inwardly from the die surface 33 and allowbarrier material to flow into them, each of these holes 40 extend toform channels or slots 41 that are inclined relative to the uppersurface 33 of the die 30. These inclined channels 41 allow barriermaterial to flow in to form the barrier walls 9 c of the co-extrudedassembly 10 as the barrier material passes through the die 30 over thesurface 33.

With reference to FIG. 5, a frontal view of the die 30 is shown whereinthe lower surface 50 of the die 30 is illustrated showing that forms thedie profile where the sealant material will pass to form the sealantstrips 11 as they pass through a plurality of spaces 51 and lateralextremes 52, 53. These lateral extremes 52, 53 are profile depressionsthat allow the axially outermost sealant strips 20, 22 to be formedwherein the intermediate zones 21 between the barrier wall 9 c formingchannels 41 are illustrated by the profile space 51 which form theintermediate sealant strips 21 in the finished assembly 10. In order toaccomplish this co-extrusion of the barrier layer 9 with inclinedbarrier walls 9 c it is important that the channels or slits 41producing the barrier walls 9 c be protected so they do not occlude withsealant material. To achieve this the die 30 is constructed with channelflow dividers 56 that project outwardly upstream of the slits 41 in sucha fashion that the sealant material will be smoothly diverted aroundthese carved projection surfaces of the flow diverters 56 as the sealantmaterial flows past surrounding the downstream slit 41 directly belowthe flow divider 56 as the barrier walls 9 c as they are being formedsuch that the sealant strips 11 simultaneously will fill the void spaces51, 52 and 53 between the barrier layer 9 and the inclined walls 9 cforming the plurality of sealant strips 11. These projections or flowdividers 56 are profiled as shown in an enlarged view in FIG. 7 of thedie 30. As shown in FIG. 7, the barrier material will flow down into theholes 40 filling the channel or slit 41 and the sealant material comingfrom the lower side will be diverted around the flow divider 56projections in such a fashion that the sealant 11 will flow back ontothe inclined walls 9 c as they are formed insuring that the entireassembly 10 is produced in a dual extrusion creating both the barrierlayer 9 with inclined walls 9 c and sealant strips 11 as a simpleco-extruded compartmentalized strip and barrier assembly 10 according tothe present invention.

With reference to FIG. 8, the die 30 is shown encased in phantom linesrepresenting the extrusion head holding the die 30. The extrusion head60 has two feed nozzles 61, 62. One feed nozzle 61 for feeding thebarrier material to form the barrier layer 9 within inclined barrierwalls 9 c as a top surface of the assembly 10 and the second extrusionnozzle 62 providing the sealant material which is shown feeding underthe die 30 to form the sealant strips 11. As shown, the output end ofthe die head has an opening 63 through which a portion of the assembledco-extruded compartmentalized sealant and barrier assembly 10 is showncoming from the opening 63. This figure is exemplary of how thecompartmentalized sealant strip and barrier assembly 10 is formed as aco-extrusion. Alternatively, it may be such that the die 30 is flippedto form the barrier as a lower surface during extrusion and then havethe assembly 10 flipped at the tire building station to insure thebarrier layer with inclined walls is the top or upper layer of theassembly 10.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be appreciated thereis still in the art various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

1. A method for making a compartmentalized sealant strip and barrierassembly comprises the steps of: co-extruding a barrier strip ofnon-sealant elastomeric material with a plurality of projecting linearextending walls and a sealant strip wherein the sealant strip is formedon one side of the barrier strip filling the space between the pluralityof projecting walls to form a plurality of linearly extending rows ofsealant across the transverse width of the co-extruded to form thecompartmentalized sealant strip and barrier assembly.
 2. The method formaking a compartmentalized sealant strip and barrier assembly of claim 1wherein the step of co-extruding further comprises the step of: formingthe projecting walls on an inclined angle relative to a planeperpendicular to the width of the strip.
 3. The method for making acompartmentalized sealant strip and barrier assembly of claim 2 whereinthe co-extruded sealant strip and barrier assembly has a center planeperpendicular to the width of the strip and the projecting walls areinclined from the barrier strip extending laterally outwardly away fromthe center plane to form a sealant barrier wall to prevent sealantmigration toward the center plane of the sealant strip and barrierassembly.
 4. The method for making a compartmentalized sealant strip andbarrier assembly of claim 1 wherein the step of co-extruding furthercomprises the step of: forming the barrier strip with lateral edges thatextend beyond the lateral outermost sealant strips on each side of theassembly, the lateral edges being bonding surfaces to seal the sealantstrip and barrier assembly into an uncured rubber layer when assembledinto an unvulcanized tire.
 5. The method for making a compartmentalizedsealant strip and barrier assembly of claim 1 wherein the barrier stripof the assembly is formed as a co-extrusion to be a top layer of thecompartmentalized sealant strip and barrier assembly when built into atire.
 6. The method for making a compartmentalized sealant strip andbarrier assembly of claim 3 wherein the inclined barrier walls areco-extruded extending a depth between 50 to 100 percent of the thicknessof the sealant strips.
 7. The method for making a compartmentalizedsealant strip and barrier assembly of claim 6 wherein the inclined wallsextend to a depth equal to the thickness of the sealant strips.
 8. Aco-extruded compartmentalized sealant strip and barrier strip assemblycomprising: a co-extrusion of barrier strips of non-sealant elastomericmaterial having a plurality of projecting linearly extending barrierwalls formed on one side of the barrier strip; and a co-extrusion of aplurality of linearly extending rows of sealant to a thickness at leastfilling spaces between the barrier walls of the barrier strip, thecombination forming the compartmentalized sealant strip and barrierassembly.
 9. A co-extruded compartmentalized sealant strip and barrierstrip assembly of claim 8 wherein the projecting barrier walls extendfrom the one side of the barrier strip to a depth between 50 to 100percent of the thickness of the sealant strips.
 10. A co-extrudedcompartmentalized sealant strip and barrier strip assembly of claim 9wherein the thickness of the sealant strips is between 0.5 to 2 cm. 11.A co-extruded compartmentalized sealant strip and barrier strip assemblyof claim 10 wherein the projecting barrier walls are inclined relativeto a plane perpendicular to a width of the strip and barrier assembly.12. A co-extruded compartmentalized sealant strip and barrier stripassembly of claim 11 wherein the co-extruded assembly has a center planeperpendicular to the width of the assembly and the projecting walls areinclined from the barrier strip extending laterally outwardly awayrelative to the center plane to form a sealant barrier to preventsealant migration toward the center plane of the assembly.
 13. Aco-extruded compartmentalized sealant strip and barrier strip assemblyof claim 8 wherein the barrier strip has a pair of lateral edges, eachlateral edge extends laterally beyond the lateral outermost sealantstrip on each side of the assembly, the lateral edges having a widthwhich provides a bonding surface to seal the sealant and barrierassembly to an uncured rubber layer when assembled into an unvulcanizedtire.
 14. A co-extruded compartmentalized sealant strip and barrierstrip assembly of claim 13 wherein the barrier strip of the assembly isa top or a radially outer layer or a radially outer layer of thecompartmentalized sealant strip and barrier assembly when built into atire.
 15. A co-extruded compartmentalized sealant strip and barrierstrip assembly of claim 8 wherein the barrier strip has a layerthickness of 1 mm to 4 mm and the projecting barrier walls have athickness equal to or less than the thickness of the layer thickness.16. A co-extruded compartmentalized sealant strip and barrier stripassembly of claim 9 wherein the barrier walls extend to the fullthickness of the sealant strips and have exposed ends.
 17. A co-extrudedcompartmentalized sealant strip and barrier strip assembly of claim 8wherein the sealant is comprised of, based upon parts by weight per 100parts by weight of said partially depolymerized butyl rubber exclusiveof carbon black: (A) a partially organoperoxide-depolymerized butylrubber as a copolymer of isobutylene and isoprene, wherein said butylrubber, prior to such depolymerization, is comprised of about 0.5 toabout 5 percent units derived from isoprene, and correspondingly fromabout 95 to about 99.5 weight percent units derived from isobutylene;(B) particulate reinforcing filler comprised of: (1) about 20 to about50 phr of synthetic amorphous silica, or (2) about 15 to about 30 phrsynthetic amorphous silica, preferably precipitated silica, and about 5to about 20 phr of clay, or (3) about 15 to about 30 phr syntheticamorphous silica and about 5 to about 20 phr of calcium carbonate, or(4) about 15 to about 30 phr synthetic amorphous silica, about 5 toabout 15 phr of clay and about 5 to about 15 phr of calcium carbonate;(C) from zero to 6 phr of short organic fibers; (D) a colorant of otherthan a black color wherein said colorant is selected from at least oneof organic pigments, inorganic pigments and dyes; and (F) from zero toabout 20 phr of rubber processing oil.
 18. A sealant tire comprises: apair of annular beads; a pair of elastomeric apexes, one apex above eachbead; at least one carcass ply extending between and wrapped about eachbead; a belt reinforcing structure overlaying the carcass; a treadoverlaying the belt reinforcing structure; an air impervious inner linerextending between the beads underlying the carcass for forming an airchamber; and a compartmentalized sealant strip and barrier assemblypositioned between the carcass and inner liner under the beltreinforcing structure, the compartmentalized sealant strip and barrierassembly characterized by: being a co-extrusion of a co-extrusion ofbarrier strips of non-sealant elastomeric material having a plurality ofprojecting linearly extending barrier walls formed on one side of thebarrier strip; and a co-extrusion of a plurality of linearly extendingrows of sealant to a thickness at least filling spaces between thebarrier walls of the barrier strip, the combination forming thecompartmentalized sealant strip and barrier assembly.
 19. The sealanttire of claim 18 wherein the co-extruded assembly has a center planeperpendicular to the width of the assembly and the projecting walls areinclined from the barrier strip extending laterally outwardly awayrelative to the center plane to form a sealant barrier to preventsealant migration toward the center plane of the assembly.
 20. Thesealant tire of claim 18 wherein the barrier strip has a pair of lateraledges, each lateral edge extends laterally beyond the lateral outermostsealant strip on each side of the assembly, the lateral edges having awidth which provides a bonding surface to seal the sealant and barrierassembly to an uncured rubber layer when assembled into an unvulcanizedtire.
 21. The sealant tire of claim 18 wherein the projecting barrierwalls extend from the one side of the barrier strip to a depth between50 to 100 percent of the thickness of the sealant strips.
 22. Thesealant tire of claim 18 wherein the barrier walls extend to the fullthickness of the sealant strips and have exposed ends.
 23. The sealanttire of claim 18 wherein the barrier strip has a layer thickness of 1min to 4 mm and the projecting barrier walls have a thickness equal toor less than the thickness of the layer thickness.
 24. An extrusion diefor forming a compartmentalized sealant strip and barrier assemblycomprises: a die having an upper surface profile with a plurality ofholes extending inwardly, each hole having a slit open to a downstreamdirection, the holes and slit provide a wall forming opening in a lowersurface profile for forming a plurality of sealant strips, and whereinthe space between the wall forming slits and the upper surface provide aplurality of spaces for sealant material to be formed in strips as asingle co-extrusion.
 25. The extrusion die for forming acompartmentalized sealant strip and barrier assembly of claim 24 whereineach slit is downstream of a flow dividing projection, the flow dividingprojection separates the sealant into strips prior to passing the slits.26. The extrusion die for forming a compartmentalized sealant strip andbarrier assembly of claim 24 wherein the slits are inclined to formangled barrier walls.